The selection of useful chemical compounds for any application can be a time consuming and expensive task. Typically, the first step is to look for signs of the desired activity in any compound available. The compounds can be natural or synthetic. Starting from a promising compound, the compound can then be modified, traditionally through one-at-a-time modifications to the structure. In the drug industry, for example, many years and hundreds of millions of dollars may be required to bring a drug to market. Therefore, attempts have been made to make the process more efficient.
More systematic approaches, generally termed combinatorial chemistry, are based on having combinatorial collections or libraries of compounds that can be screened for activity. A library can be constructed based on general chemical principles. The library is then input into a systematic development process. Examples of systematic development processes include a parallel synthesis approach and a split-and-mix synthesis approach.
In the parallel synthesis approach, the building blocks for a study are placed in separate reaction vessels, generally wells of a microtitre plate. The appropriate syntheses can be carried out in each well to produce a set of products. These can then be used in efficacy screening, toxicity studies, and the like. Efficacy screening can involve tests for biological activity or any other chemical property.
In a split-and-mix synthesis, a series of first reactants are attached to polystyrene beads. These attached reactants are mixed together and split into a series of vessels, tubes or wells. A different second reactant is added to each vessel. If a third reactant is involved, the second group is again mixed together and split. A different third reactant is added to the tubes containing the second mixtures. The most potent of the final mixtures are determined. A variety of techniques can be used to ascertain the most potent combination.
While drug design is a significant application of these techniques, these combinatorial chemistry approaches can be used for the production of chemicals for any application. For example, they have also been used to identify high temperature superconductors, liquid crystals for flat panel displays, and materials for constructing batteries. The assays incorporated into the techniques are appropriate for the type of compound desired. Basic to the application of these development programs is the construction of a suitable library of chemicals.